In many operations employing a mixture of fluids, it is important to insure that the concentration of one of the fluids be maintained below a particular level. Illustrative of such a situation is the employment of a mixture of carbon monoxide and nitrogen gases as a medium for preserving certain foodstuffs while in transit. It has previously been suggested to introduce the nitrogen and the carbon monoxide separately into the shipping container, such as for example, the cargo compartment of a vehicle. Typically, the shipping container is first loaded with foodstuffs and then the carbon monoxide and nitrogen are introduced to replace the air in the container. The introduction of carbon monoxide directly into air is obviously a risky operation. Even when an effort is made to sweep the air from the containers, such as, for example, by a nitrogen purge, prior to introduction of carbon monoxide, it is still possible for isolated pockets of air to be present within the confined spaces of the container into which pure carbon monoxide is being injected. Such procedures make it possible for explosive mixtures of carbon monoxide and air to exist and, in fact, several explosions have occurred.
This particular type of problem is solved through the present invention by the method of blending the carbon monoxide and nitrogen together outside of the container before dispensing the mixture into the shipping container, thereby avoiding the dangerous practice of introducing pure carbon monoxide directly. Additionally, the present invention functions to insure that the carbon monoxide content in the mixture with nitrogen is maintained at a level below that at which carbon monoxide could form an explosive mixture with air.
While techniques are available for analyzing and detecting the compositions of fluid mixtures which can be operable to adjust the proportions of the components of the mixture to insure maintenance of a desired composition of the mixture, many of such procedures are time consuming and in other instances, the apparatus required to effect such control is quite cumbersome. Accordingly, the need has been felt in the art for a simple procedure, capable of being implemented by inexpensive and compact apparatus, which will assure prevention of the formation of dangerous concentrations of a component in a mixture.